The Megamouth Shark (Megachasma pelagios) is an extremely
rare and unusual species of shark, discovered in 1976, with 36 specimens
known to be caught or sighted as of 2006. Like the basking shark
and whale shark, it is a filter feeder, consuming plankton and jellyfish,
and is distinctive for its large head with rubbery lips. It is so
unlike any other type of shark that it is classified in its own
family Megachasmidae, though it has been suggested that it may belong
in the family Cetorhinidae of which the Basking shark is currently
the sole member.

The appearance of the Megamouth is distinctive. It has a large mouth
with small teeth, a broad rounded snout (observers have mistaken
it for a young orca), a generally brownish-blackish color on top
and white underneath, and an asymmetrical tail with a long upper
lobe, similar to the Thresher Shark. The interior of its gill slits
are lined with finger-like gill rakers that capture its food. A
relatively poor swimmer, the Megamouth has a soft, flabby body and
lacks keels.

The first Megamouth was captured on November 15, 1976 about 25 miles
off the coast from Kaneohe, Hawaii when it became entangled in the
sea anchor of a United States Navy ship. Examination of the 4.5
m (14.6 ft), 750 kg (1,650 lb) specimen by Leighton Taylor showed
it to be an entirely unknown type of shark, rivaling the coelacanth
as the most sensational discovery in ichthyology during the 20th
century.

The long delay between initial discovery (1976) and the scientific
description (1983), became the focus of an elaborate practical joke
by two friends of Leighton Taylor, Richard Ellis of the American
Museum of Natural History and John McCosker, director of San Francisco's
Steinhart Aquarium. Ellis and McCosker photocopied random articles
from Japanese scientific journals and inserted photographs of the
megamouth shark and a map of the type location and an English abstract,
making it appear as if a Japanese team under guidance of John E.
Randall of the Bishop Museum was to snatch the scientific merits
of the description right from under Taylor's nose. An accomplice
in Japan then mailed the "preprints" to Taylor, who was
naturally dumbstruck. He then had his Japanese-American secretary
translate the "paper", only to be told that it contained
things like musings about the cat in Japanese art, and rhinoceroses
in Ueno Zoo, but nothing about the megamouth shark. Hidden on the
last page were the names of Ellis and McCosker, put there deliberately
for Taylor to find them. Realizing he had been had, Taylor finally
wrote up the description. The remark on its last page, "Particular
thanks go to Richard Ellis and John McCosker for preparation of
a preliminary manuscript which was of great help in the production
of this final paper," is in reference to this incident.

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